Mutation at a single position in the V2 domain of the HIV-1 envelope protein confers neutralization sensitivity to a highly neutralization-resistant virus.

Department of Biomolecular Engineering, Baskin School of Engineering, University of California, Santa Cruz, 1156 High Street, MS-SOE2, Santa Cruz, CA 95064, USA.
Journal of Virology (Impact Factor: 4.65). 11/2010; 84(21):11200-9. DOI: 10.1128/JVI.00790-10
Source: PubMed

ABSTRACT Understanding the determinants of neutralization sensitivity and resistance is important for the development of an effective human immunodeficiency virus type 1 (HIV-1) vaccine. In these studies, we have made use of the swarm of closely related envelope protein variants (quasispecies) from an extremely neutralization-resistant clinical isolate in order to identify mutations that conferred neutralization sensitivity to antibodies in sera from HIV-1-infected individuals. Here, we describe a virus with a rare mutation at position 179 in the V2 domain of gp120, where replacement of aspartic acid (D) by asparagine (N) converts a virus that is highly resistant to neutralization by multiple polyclonal and monoclonal antibodies, as well as antiviral entry inhibitors, to one that is sensitive to neutralization. Although the V2 domain sequence is highly variable, D at position 179 is highly conserved in HIV-1 and simian immunodeficiency virus (SIV) and is located within the LDI/V recognition motif of the recently described α4β7 receptor binding site. Our results suggest that the D179N mutation induces a conformational change that exposes epitopes in both the gp120 and the gp41 portions of the envelope protein, such as the CD4 binding site and the MPER, that are normally concealed by conformational masking. Our results suggest that D179 plays a central role in maintaining the conformation and infectivity of HIV-1 as well as mediating binding to α4β7.

Download full-text


Available from: Sara M O'Rourke, Jan 30, 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: The 24h molecular clock that ticks in organisms from bacteria to humans is useless without an output signal. The 18 amino acid neuropeptide, the pigment dispersing factor (PDF) encoded by the pdf gene, is the key outgoing signal in behavioral circadian rhythms in Drosophila melanogaster. PDF is likely to act on clock neurons in an autocrine or paracrine fashion. In this study, we identify the PDF receptor, which belongs to the G-protein coupled receptor family. We cloned the ORF of gene CG13758 and this resulted in a gene product of 669 amino acids, which did not correspond to the predicted protein length in the Drosophila database. Functional expression of this orphan receptor in HEK-293 cells and screening with a synthetic peptide library revealed that Drm-PDF specifically activates the receptor in a dose-dependent way. No other peptides were able to elicit a calcium response. These results indicate that we have cloned and identified the Drosophila PDF receptor.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The CD4 binding site (CD4bs) on the HIV-1 envelope plays a major role in determining the capacity of R5 viruses to infect primary macrophages. Thus, envelope determinants within or proximal to the CD4bs have been shown to control the use of low CD4 levels on macrophages for infection. These residues affect the affinity for CD4 either directly or indirectly by altering the exposure of CD4 contact residues. Here, we describe a single amino acid determinant in the V1 loop that also modulates macrophage tropism. Thus, we identified an E153G substitution that conferred high levels of macrophage infectivity for several heterologous R5 envelopes, while the reciprocal G153E substitution abrogated infection. Shifts in macrophage tropism were associated with dramatic shifts in sensitivity to the V3 loop monoclonal antibody (MAb), 447-52D and soluble CD4, as well as more modest changes in sensitivity to the CD4bs MAb, b12. These observations are consistent with an altered conformation or exposure of the V3 loop that enables the envelope to use low CD4 levels for infection. The modest shifts in b12 sensitivity suggest that residue 153 impacts on the exposure of the CD4bs. However, the more intense shifts in sCD4 sensitivity suggest additional mechanisms that likely include an increased ability of the envelope to undergo conformational changes following binding to suboptimal levels of cell surface CD4. In summary, we show that a conserved determinant in the V1 loop modulates the V3 loop to prime low CD4 use and macrophage infection.
    Journal of Virology 03/2011; 85(5):2397-405. DOI:10.1128/JVI.02187-10 · 4.65 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: HIV-1 is capable of mimicking the ligand of integrin α(4)β(7) by displaying a tripeptide mimotope on the V2 region. Through this mimicry HIV can bind the α(4)β(7) integrin and get carried through the lymphocyte proliferation signaling pathway, cell-to-cell adhesion and can migrate to gut-associated lymphoid tissues. The same tripeptide motif was suggested to be the epicenter of neutralization in laboratory strains of HIV-1. In this study, we compared the α(4)β(7) binding sites of two HIV-1 subtypes prevalent in China and found that the tripeptide binding domain of α(4)β(7) was more diverse in subtype B' strains than in CRF07_BC.
    AIDS Research and Human Retroviruses 03/2011; 27(10):1127-33. DOI:10.1089/AID.2011.0007 · 2.46 Impact Factor